Battery pack having flexible circuit connector

ABSTRACT

A battery pack containing a plurality of battery modules, these modules comprising a plurality of individual battery units, these battery units comprising a plurality of bicells with opposing terminals. The battery modules are connected in series by use of a flexible circuit and by opposing positive and negative terminals of each battery unit. The terminals of each battery unit contain a region of apertures which allow the adhesive of the packaging material to seal more effectively, thereby eliminating or reducing the amount of leakage from an individual battery unit.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to battery packs and components thereof.

2. Description of the Related Art

Conventional lithium polymer soft pack batteries use prismatic orcylindrical cans or rectangular boxes as a package for the battery cellsas seen by reference to U.S. Pat. No. 5,639,571 issued to Waters, et al.However, these packages are heavy and expensive, which aredisadvantages. In addition, conventional lithium polymer soft packbatteries further use nickel, copper or aluminum terminals to carrycurrent through the package seal to the outside for connection to anoverall package connector. These terminals are arranged to exit the sameside of the package and are adjacent to each other. The foregoing“same-side” arrangement, however, has shortcomings.

One of the problems involves leaking of the electrolyte solution at aseal point of the terminal to the package. Another problem relates tothe orientation of the terminals on the same side. Specifically, theterminals are arranged to exit on the same side of the package and areadjacent to each other, making it difficult to electrically connect thepackages in a compact configuration.

There is therefore a need for an improved battery pack that minimizes oreliminates one or more of the problems set forth above.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a solution to one ormore of the above mentioned problems. In one aspect of the presentinvention, a battery pack is provided that includes a flexibleconnective circuit containing conductive traces and flaps extending fromwindows cut from a substrate thereof. One advantage is that these tracesand flaps allow for power and control electrical connections between andamong a plurality of battery modules in a reduced weight arrangement.Additionally, the flexible circuit allows battery modules to beconnected in series (for greater output voltage), or in parallel (forgreater ampacity).

According to the first aspect, a battery pack is provided that includesa plurality of battery modules each having at least a positive terminaland a negative terminal associated therewith, and a flexible circuitconfigured to connect the plurality of positive and negative terminalsto an overall output of the battery pack. In a preferred embodiment,each module includes a plurality of individual battery units (sometimesreferred to as a “soft pack”), each battery unit including a pluralityof bicells.

In a second aspect of the present invention, a pair of terminalsassociated with a battery unit are located on opposing sides of thebattery unit, allowing the battery unit to be rotated one relative to anadjacent one and placed directly thereon. The process can be repeated toform battery modules. This arrangement allows a compact stacking ofbattery units.

According to the second aspect, a battery unit is provided that includesa (i) plurality of bicells, each bicell containing anodic exposed gridsand cathodic exposed grids, the cathodic exposed grids being locatedacross the bicell on the other side of the anodic exposed grids, (ii) apositive terminal, (iii) a negative terminal that is located across thebicell on the other side of the positive terminal, and (iv) a packagingenvelope. In a preferred embodiment, a plurality of battery units areeach stacked upon the previous battery unit, having been rotated 180degrees around an axis.

In a third aspect of the present invention, a terminal for a batteryunit includes a region that contains through apertures along a lengthdimension of the terminal. The apertures allow an adhesive or the liketo flow through the apertures from a first side to a second side of theterminal to thereby form an improved seal. Additionally, in a preferredembodiment, a convoluted arrangement of apertures is used which presentsa corresponding convoluted edge path. Such a path would require anelectrolyte solution to travel a further distance before it could leakthrough the individual battery cell package, thereby reducing oreliminating the occurrence of leaking.

According to the third aspect, a terminal for a battery unit is providedthat includes an electrically conductive body portion having a main axisassociated therewith, including a first region configured to be adheredto and in electrical contact with exposed bicell grids, a second regionextending along the axis and having a plurality of aperturestherethrough, a third region encapsulated by an electrical insulatingmaterial, and a fourth region configured for electrical connection to aconductor.

Other features, objects, and advantages will become apparent to one ofordinary skill from the following detailed description and accompanyingdrawing illustrating the invention by way of example but not by way oflimitation.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is an exploded, perspective view of the battery pack having aplurality of battery modules, according to the invention.

FIG. 2 is a schematic and block diagram view of the battery pack of FIG.1 coupled to a charger and load.

FIG. 3 is a perspective view of an individual battery unit of a batterymodule.

FIGS. 4A-4F shows the creation of an orientation of stacked batteryunits of a battery module.

FIG. 5 is a perspective view showing, in greater detail, the terminal ofFIG. 3.

FIG. 6 is a perspective view showing, in greater detail, apertures ofFIG. 5.

FIG. 7 is an enlarged view of a preferred pattern for the apertures ofFIG. 6.

FIG. 8 is a section view taken substantially along lines 8—8 of FIG. 6,showing, in greater detail, the cut-through pattern of the perforatedarea of the terminal.

FIG. 9 is a section view taken substantially along lines 9—9 of FIG. 5,showing, in greater detail, a region enclosed by an insulator.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring now to the drawings wherein like reference numerals are usedto identify identical components in the various views, FIG. 1illustrates an improved battery pack 10 according to the invention. Thepack 10 may be used for portable or stationary electrical and/orelectronic devices, including commercial apparatus such as medicaldevices. In addition, to enhance understandability, a general overviewof the basic stackup of battery components will be set forth. The basiccomponent of the battery pack 10 is a so-called bicell, as know in theart, for example, by reference to U.S. Pat. No. 6,063,519 issued toJeremy Barker, et al. A plurality of bicells are arranged, as will beseen, to form a battery unit, sometimes referred to as a soft-pack. Aplurality of battery units are arranged together to from a batterymodules which has terminals for delivering power. Finally, a pluralityof battery modules are arranged to form the overall battery pack. Thus,the progression is as follows: bicell→battery unit→batterymodule→battery pack.

Battery pack 10 may include a plurality of battery modules 12 ₁, 12 ₂,to 12 _(n), where n is an integer, a flexible circuit 14, and a case 16with a top 18.

The battery modules 12 _(n) may be rechargeable lithium polymer (LiPo)battery modules configured to provide electrical power. Otherchemistries, such as other lithium chemistries, may also be used. Eachbattery module 12 _(n) may include a plurality of individual batteryunits 20 (as shown in FIGS. 3-4A-F), one or more positive terminals 22,and one or more negative terminals 24. Each terminal 22, 24 may have arespective tang 26.

The flexible circuit 14 is configured to establish control and powerconnections between and among the individual battery modules 12 _(n),the case 16 and other electronics to be described below. In theillustrated embodiment, flexible circuit 14 couples the battery modules12 _(n) in a series-connected arrangement, and allows electrical powerto flow in (charge) and out (discharge) of case 16. In this regard,flexible circuit 14 may include a substrate 28, a plurality of windows30, a plurality of conductive traces 31, a plurality of flaps 32, andone or more jumpers 34. Flexible substrate 28 may be generally flexible,and may be of a material such as MYLAR® by E. I. Du Pont de Nemours andCompany or the like. Substrate 28 is configured to contain a number ofconductive traces 31 for establishing the above mentioned connections.Conductive traces 31 may run along the length of the substrate 28 andmay be made of copper or another conductive material. Flexible circuit14 may also include one or more windows 30 cut from substrate 28. Flaps32 made of a conductive material, such as copper, fold out from windows30, the conductive material being exposed once one side of the flexiblesubstrate 28 is removed from the cut window 30 and the remainingsubstrate 28 and conductive material are folded to create window 30 andflap 32. Flaps 32 are electrically connected to conductive traces 31.

Windows 30 may be oversized to allow for thermal expansion of flaps 32when flaps 32 are electrically connected to terminals 22, 24. In apreferred embodiment, negative terminal 24 of each battery unit 20 isultrasonically welded to corresponding flap 32 on flexible circuit 14via tang 26. Other conventional connection methods may be employed.Flexible circuit 14 may also include one or more jumpers 34, which allowthe connection of battery modules 12 _(n) in a series-connectedarrangement. It should be appreciated that jumpers 34 permit connectionsover conductive traces 31 without being electrically connected to traces31 themselves.

Flexible circuit 14 may also include a controller connector 36, a packconnector 38, a fuse 40, and a current sensor 42, all of which areelements known to those with ordinary skill in the art. Controllerconnector 36 provides electrical and mechanical termination of variouspower and control signals between a controller (best shown in FIG. 2)dedicated to pack 10 and flexible circuit 14. Overall pack connector 38comprises a pair of mating portions 38 ₁ and 38 ₂, and provides powerand control from inside battery pack 10 to the outside world. Fuse 40and sensor 42 provide their conventional functions. Particularly, fuse40 is configured to “open” electrically when a predetermined current(e.g., a DC current) is being sourced by pack 10. Sensor 42 generates acurrent indicative signal representing the level of DC current beingprovided by pack 10. Flexible circuit 14 may also include a living hinge44 which allows flexible circuit 14 to be oriented such that thelocation of selected windows 30 and flaps 32 can be configured toelectrically connect to terminals 22, 24 of end module 12 _(n). Theremay be, however, no hinges or bends or several, depending on theparticular design of the case.

FIG. 1 also shows a case 16 and top 18 which cooperate to enclose andprotect the interior components of battery pack 10, namely modules 12and flexible circuit 14. The case 16 includes a bottom 46, two end walls48, 50 and two side walls 52, 54 which form an interior 56. Interior 56houses, in effect, modules 12 and flexible circuit 14. Case 16 and top18 may comprise electrical insulating material, for example a polyesteror a plastic.

FIG. 2 shows, in schematic and block diagram form, battery pack 10 ingreater detail as employed in a preferred environment, specificallyfurther including a battery controller 58, package connector 38comprising a positive polarity (+) terminal 60 and a negative polarity(−) terminal 62, communication terminals such as a transmit (Tx)terminal 64 and a receive (Rx) terminal 66, and a control terminal suchas a charge circuit line 68. FIG. 2 further shows a master controller70, a charger 72, a power source 74, and an electrical load 76.

In operation, pack 10 may be used to provide (discharge) power to a load76 or to receive power (recharge) through a charger 72. Positivepolarity terminal 60 is connected to charger 72, which is also connectedto current sensor 42. Both charger 72 and current sensor 42 areconnected to battery controller 58 through battery controller connector36. Negative polarity terminal 62 is also connected to charger 72 andfuse 40. Transmit terminal 64 is connected to battery controller 58through controller connector 36 and to master controller 70 through packconnector 38. Receive terminal 66, which is connected to batterycontroller 58 through controller connector 36 and is also connected tomaster controller 70 through pack connector 38. Charge circuit line 68,which is connected to battery controller 58 through controller connector36, is also connected to master controller 70 through pack connector 38.

When the battery pack is providing power to a load 76, master controller70 allows the positive and negative polarity terminals 60, 62 to passthrough charger 72 to power load 76. When battery pack 10 needsrecharging, as determined by master controller 70, the terminal leads60, 62 are reconfigured so as to be recharged by charger 72 connected topower source 74. Master controller 70 determines charge or rechargeconfiguration dependent upon information supplied by battery controller58. Voltage information is supplied to battery controller 58 viacontroller connector 36, which is connected to transmit terminal 64 andreceive terminal 66. Transmit terminal 64 and receive terminal 66 sendand obtain voltage information about individual battery units 20,individual battery modules 12, and the overall battery pack 10,information which has been collected via the electrical connection ofterminals 22, 24 of battery units 20 (plurality of units 20 comprisingbattery modules 12) to flexible circuit 14 via flaps 32.

In a preferred embodiment, battery units 20 are electrically connectedin a series-connected arrangement (shown best by FIG. 4). Each negativeterminal 24 of the individual battery units 20 (which is electricallyconnected to positive terminal 22 of adjacent battery unit 20, connectedin series) is electrically connected to flexible circuit 14 via flaps32. This is accomplished by ultrasonically welding tang 26 of negativeterminal 24 to corresponding flap 32 in flexible circuit 14. Aspreviously discussed each flap 32 corresponds to electrically conductivetrace 31 running through flexible circuit 14. Traces 31 connect tocontroller connector 36. Because each battery unit 20 _(n) is connectedto flexible circuit 14 and adjacent battery unit 20 _(n+1), a voltagelead for each battery unit 20 _(n) is produced, which allows the voltagelevel of each battery unit 20 _(n) to be read individually by batterycontroller 58. The voltage level information may be transmitted andreceived, via transmit terminal 64 and receive terminal 66, respectivelyto overall controller 70. Therefore, both the overall battery pack 10voltage as well as the voltages of the individual battery cells 20 maybe monitored. Positive terminal 22 of the end battery unit 20 isconnected to the flexible circuit 14 although positive terminal 22 doesnot include a tang 26 in this embodiment. This connection isaccomplished by ultrasonically welding negative terminal 24 to positiveterminal 22 and ultrasonically welding tang 26 of negative terminal 24to corresponding flap 32 of flexible circuit 14.

Battery controller 58 may be configured to request recharge of batterypack 10 or one or more individual battery units 20 via charge circuitline 68, dependent upon the voltage readings of the individualcomponents and overall battery pack 10. Use of the flexible circuit 14to electrically connect battery modules 12, allows acquisition ofinformation about each battery unit 20, each battery module 12, andbattery pack 10 while providing a reduced-weight arrangement forelectrically connecting the individual battery units 20 and batterymodules 12.

Connecting battery modules 12 to each other via flexible circuit 14allows flexibility of battery pack 10 in at least two ways. First, thereexists electrical flexibility. Terminals 22, 24 which connect modules 12to flexible circuit 14 also provide a voltage lead for each individualbattery unit 20. Additionally, terminals 22, 24 enable voltage sensingof individual modules 12 and the overall battery pack 10. Moreover, theflex circuit 14 can be configured to couple the plurality of batterymodules in parallel, thereby increasing amperage capacity (ampacity).Alternatively, flexible circuit may be configured to couple theplurality of modules in series, thereby increasing output voltage. Stillfurther, the flex circuit can be configured to allow one tier, twotiers, or more of battery modules. The foregoing can be accomplished viaappropriate routing and interconnection of traces 31 and/or jumpers.

Second, a mechanical flexibility exists. Due to the flexibility ofsubstrate 28, modules 12 can be oriented easily in various heights,widths, and depths. Flaps 32 in flexible circuit 14 may be oriented tocorrespond with terminals 22, 24 for electrical connection. The firstaspect of the invention shows a battery pack 10 that is simpler toassemble, that uses electrical connections to both connect batterymodules 12 and battery units 20 and obtain voltage information aboutindividual modules 12 and battery units 20, and that allows numerousorientations and sizes of the battery pack 10 because of the use of theflexible circuit 14.

In another aspect of the invention, FIG. 3 shows an individual batteryunit 20 in greater detail, and in various phases of constructions. Aplurality of units 20 make up a module 12. An exploded view isdesignated 20 _(START), an intermediate phase of construction isdesignated 20 _(INT), and a finished phase of construction is designated20 _(FINISH). FIG. 3 shows a plurality of bicells 78, a packagingenvelope 80, an axis 82, adhesive layer 83, a first side of the batteryunit 84, a second opposing side of the battery unit 86, a cover strip85, positive polarity exposed grids 88, and negative polarity exposedgrids 90, a vent 92, and a direction of rotation 94 relative to axis 82.

Bicells 78 may comprise conventional bicells known to those of ordinaryskill in the art, for example as seen by reference to U.S. Pat. No.6,063,519, issued to Barker, et al., hereby incorporated by reference.As to the present invention, bicells 78 of battery unit 20 are connectedin a parallel electrical relationship. The exposed grids 88, 90 arecurrent carriers. The cathodic grids 88 are ultrasonically weldedtogether leaving just an overall top and bottom surface thereof exposed.The anodic grids 90 are ultrasonically welded together leaving just anoverall top and bottom surface exposed.

As described in the Background, a problem with conventional arrangements(i.e., terminals on the “same side” of a battery unit), is that itbecomes more difficult to connect multiple battery units in a compact,series-connected arrangement. According to the invention, eachindividual battery unit 20 has a positive terminal 22 located at a firstend 84 of the battery unit 20 and a negative terminal 24 located at asecond end 86. The second end 86 is located on an opposing side ofbattery unit 20 from first end 84, relative to a horizontal axis 82. Inthe illustrated embodiment, negative terminal 24 is ultrasonicallywelded to the remaining exposed top surface of anodic grids 90. In theillustrated embodiment, the positive terminal 22 is ultrasonicallywelded to the remaining exposed bottom surface of cathodic grids 88. Thecover strip 85 is made of the same material as the correspondingterminal (positive or negative) 22, 24 and grid (positive or negative)88, 90 and is placed above the grids 88, 90 or below the grids 88, 90,depending upon whether the terminal 22, 24 is either welded on the topof the stack of grids 88, 90 or below the stack of grids 88, 90. Thatis, the cover strip is placing on the opposing side relative to theterminal. That way, an electrosonic welding horn has opposing, reactionsurfaces to grip. The strips minimize damage to the relatively fragilegrid portion during welding.

The plurality of bicells 78 is enclosed in packaging envelope 80.Packaging envelope 80 may comprise a single sheet which is folded toenclose the bicells 78. Packaging envelope 80 may be a type oflaminated, aluminized flexible material which contains four layers. Theoutside layer exposed to the environment is an electrical insulatingmaterial, for example, a polyester. The next underlying layer ismetallic, for example, aluminum. This metallic layer reduces oreliminates the amount of moisture outside of the packaging envelope 80to which the battery unit 20 is exposed (i.e., provides a bidirectionalmoisture barrier). The third layer is of the same material as theoutside layer. The fourth layer, layer 83, comprises an adhesive such asa conventional sealing hot melt adhesive, for example ethylene acrylicacid (EAA). The part of a sheet of packaging envelope 80 is placed underthe individual battery unit 20 and a remaining part of the packagingenvelope 80 is folded over the battery unit 20 such that the hot meltadhesive layer 83 comes in contact with itself in three locations. Itcomes in contact with itself on a first end 84 and a second end 86 andedge 91 along the axis of the fold. Packaging envelope 80 contains avent 92, which allows any gas due to overcharging or other conditions toescape.

In another aspect of the present invention, opposing terminals 22, 24allow the individual battery units 20 to be bussed as battery modules 12in a compact form. An individual battery unit 20 can be rotated aroundhorizontal axis 82 in a clockwise direction 94 by 180 degrees and placedon top of another battery unit 20.

FIGS. 4A through 4F show one construction process for a preferredembodiment of the invention. A first battery unit 201, and additionalbattery units 20, are configured the following way. Positive terminals22 (e.g., aluminum) and negative terminals 24 (copper) of battery units20 are oriented such that negative terminal 24 is electrically connectedto the top surface of ultrasonically welded anodic exposed grids 90 andpositive terminal 22 is electrically connected to the bottom surface ofthe ultrasonically welded cathodic exposed grids 88. A second batteryunit 20 ₂ is placed adjacent first battery unit 20 ₁ (FIG. 4A) such thatpositive terminal 22 on bottom surface of second battery unit 20 ₂ iselectrically connected to negative terminal 24 on top surface of firstbattery unit 20 ₁ (FIG. 4B). Second battery unit 20 ₂ is rotatedclockwise about 180 degrees 94 around horizontal axis 82 such thatnegative terminal 24 of second battery unit 20 ₂ is oriented abovepositive terminal 22 of first battery unit 20 ₁ (FIG. 4C). A thirdbattery unit 203 may be placed on second battery unit 20 ₂ such thatpositive terminal 22 on bottom surface of third battery unit 20 ₃ iselectrically connected to negative terminal 24 on top surface of secondbattery unit 20 ₂ (FIG. 4D). No rotation 94 of third battery unit 20 ₃is required. A fourth battery unit 20 ₄ may be oriented as secondbattery unit 20 ₂ such that positive terminal 22 on bottom surface offourth battery unit 20 ₄ is electrically connected to negative terminal24 on top surface of third battery unit 20 ₃ (FIG. 4E). Fourth batteryunit 20 ₄ is rotated clockwise about 180 degrees 94 around horizontalaxis 82 such that negative terminal 24 of fourth battery unit 20 ₄ isoriented above positive terminal 22 of third battery unit 20 ₃ and firstbattery unit 20 ₁ (FIG. 4F). This “stacking” of successive battery units20 can be repeated for a plurality of battery units 20. Note, in aconstructed embodiment, positive terminal 22 does not generally includea tang 26. However, respecting FIG. 4F, the bottom terminal designatedT_(BOTTOM), may include a tang electrically connected thereto so as tofacilitate connection to flexible circuit 14. The overall positiveterminal of module 12 in T_(BOTTOM), while the overall negative terminalof module 12 is designated T_(TOP). Each node, it should be appreciated,also includes at least one tang, owing to the presence of a negativeterminal. This allows voltage sensing for each unit 20.

By placing negative terminal 22 on a second end 86 opposing positiveterminal 24 with respect to a horizontal axis 82, a more compactstacking of battery units 20 to create a battery module 12 is available.This is another aspect of the invention.

In another aspect of the invention, FIG. 5 shows terminal 24 in greaterdetail. Terminal 24 comprises an electrically conductive tab and may beformed of copper or aluminum material. Terminal 24 allows individualbattery unit 20 to be electrically connected to another individualbattery unit 20, the flexible connection 14, or another electricalconnection. The terminal 24 has a first region 96, a second region 98_(a) having apertures 99 _(a), a third region 100, a fourth region 102,a first locating hole 104 and a second locating hole 106. In theillustrated embodiment, terminal 24 has a tang 26 protruding from oneedge of third region 100 along a lengthwise axis 101. The first region96 may be welded to the exposed grids 90 of the plurality of bicells 78.

In a first embodiment, apertures 99 _(a) in region 98 _(a) are arrangedin a repeating pattern and comprise a standard slot, I-shape throughaperture. This allows adhesive to flow therethrough.

FIG. 6 shows a second embodiment of second region, designated 98 _(b).The second region 98 _(b) contains apertures 99 _(b) cut throughterminal 24. In the illustrated embodiment, apertures 99 _(b) runsubstantially the length of terminal 24. Packaging envelope 80 seals toitself through the apertures of second region 98 _(b) at the sides 84,86 because of the hot melt adhesive flows from above and below theapertures 98 _(b) to adhere to itself. The apertures 98 _(b) reduce oreliminate leaks of electrolyte solution from bicells 78 in at least twoways. First, the apertures 98 _(b) allow packaging envelope 80 to moreeffectively seal because the hot melt adhesive binds with itself.Second, the design of the apertures 98 _(b) creates a convoluted path bywhich the electrolyte solution must travel in order to leak from bicell78.

FIG. 7 shows an enlarged view of a repeating pattern of apertures 98_(b) referred to in the encircled region designated “7” in FIG. 6. FIG.7 shows a first axis 108, a transverse axis 110, L-shaped apertures 112,and I-shaped apertures 114. I-shaped apertures 114 are cut along ahorizontal axis 108. I-shaped apertures 114 are located between sets ofL-shaped apertures 112, wherein the long leg of the L-shaped aperture islocated along the direction of transverse axis 110. There may be fourorientations of L-shaped apertures 112 _(a), 112 _(b), 112 _(c), 112_(d). A first orientation 112 _(a) is oriented as the letter “L” in theconventional manner. A second orientation 112 _(b) is the mirror imageof the first orientation 112 _(a), the image being reflected withrespect to transverse axis 110. This second orientation resembles abackward letter “L”. A third orientation 112 _(c) is the mirror image of112 _(a), the image being reflected through horizontal axis 108. Afourth orientation 112 _(d) is the mirror image of second orientation112 _(b), the image being reflected through horizontal axis 108. Asviewed along transverse axis 110, a first pattern 113 is located above asecond pattern 115. As described along horizontal axis 108, firstpattern 113 may include one third orientation L-shaped aperture 112_(c), followed by one fourth orientation L-shaped aperture 112 _(d).Between the long legs of two L-shaped apertures 112 _(c), 112 _(d) islocated one I-shaped aperture 114 aligned along the horizontal axis 108.As described along horizontal axis 108, second pattern 115 may includeone first orientation L-shaped aperture 112 _(a), followed by a secondorientation L-shaped aperture 112 _(b). Between the long legs of the twoL-shaped apertures 112 _(a), 112 _(b) is located one I-shaped aperture114 aligned along the horizontal axis 108.

FIG. 8 is a section view taken substantially along lines 8—8 in FIG. 6and shows a first side 120 and a second side 122 of terminal 24 insecond region 98 _(b). This better illustrates how the apertures 98 _(b)allow the hot melt adhesive of the packaging 80 to seal with itself.

FIG. 9 is a section view taken substantially along lines 9-9 in FIG. 5and shows an electrical insulator 124 applied to the fourth region 102of the terminal 24. Insulator 124, such as a polyester, may be appliedin the form of a tape or may be applied at the time of manufacture ofterminal 24. These methods are known to those of ordinary skill in theart. Insulator 124 is applied to first side 120 of terminal 24, secondside 122 of terminal 24, and edge 126 of terminal 24. Placement ofinsulator 124 reduces or eliminates shorting of terminal 24 that couldbe created if terminal 24 comes in contact with the aluminum layer ofpackaging envelope 80.

Terminal 24 may contain first locating hole 104 and second locating hole106. These holes 104, 106 may aid in welding of terminal 24 to exposedgrids 88, 90 of plurality of bicells 78 and manufacture of battery unit20 by aiding in alignment of components for sealing.

It should be understood that although FIG. 5 illustrates tang 26, tang26 is not required for the invention. In a preferred embodiment,positive terminal 22 excludes tang 26, and negative terminal 24 includestang 26, tang 26 being the location of electrical connection of batteryunits 20 to flexible circuit 14. Terminal 24 (including or excludingtang 26) aids in the sealing of packaging envelope in at least two ways.Apertures 99 _(a), 99 _(b) allow hot melt adhesive of packaging envelope80 to seal to itself. Further, apertures 99 _(b) create a convolutedpath, making it more difficult for electrolytic solution to leak frompackaging envelope 80. In one embodiment, terminal 24 may include a tang26 that aids in connection of battery unit 20 to flexible circuit 14.Terminal 24 is another aspect of the invention.

What is claimed is:
 1. A battery pack, comprising: a plurality ofbattery modules each having at least one positive terminal and onenegative terminal associated therewith, wherein at least one of saidbattery module terminals includes a respective tang that is integral tothe terminal; and a flexible circuit configured to connect saidplurality of positive and negative terminals to an output of saidbattery pack, wherein said flexible circuit further includes windowsconfigured to allow said tangs to pass through, wherein an edge of saidwindow defines a hinged edge for a flap configured such that said flapsare in registry with said tangs and at least one of said battery moduleterminals is electrically connected to said flap via said tang.
 2. Thebattery pack of claim 1, wherein at least one of said battery modulescomprises a plurality of individual battery units, each battery unitincluding at least one positive terminal and one negative terminal. 3.The battery pack of claim 2, wherein at least one of said battery unitsincludes a plurality of bicells.
 4. The battery pack of claim 1, whereinsaid flexible circuit further comprises a plurality of jumpers.
 5. Thebattery pack of claim 1, wherein said flexible circuit further comprisesa controller connector, said controller connector being configured toreceive a battery controller, said connector being further configured tobe in sensing relation to each battery module.
 6. The battery pack ofclaim 1, wherein said flexible circuit further comprises a fuse.
 7. Thebattery pack of claim 1, wherein said flexible circuit further comprisesa pack connector.
 8. The battery pack of claim 1, wherein said flexiblecircuit further comprises a current sensor.
 9. The battery pack of claim1, further comprising at least one living hinge formed along a flex lineon said flexible circuit.
 10. A battery pack, comprising: a plurality ofbattery modules each having at least a positive terminal and a negativeterminal associated therewith, wherein at least one of said batterymodules comprises a plurality of individual battery units, each batteryunit including at least one positive terminal and one negative terminal,wherein at least one of said battery unit terminals includes arespective tang that is integral to the terminal; and a flexible circuitconfigured to connect said plurality of positive and negative batteryunit terminals to an output of said battery pack, wherein said flexiblecircuit further includes windows configured to allow said tangs to passthrough, wherein an edge of said window defines a hinged edge for a flapconfigured such that said flaps are in registry with said tangs and atleast one of said battery unit terminals is electrically connected tosaid flap via said tang.
 11. The battery pack of claim 10, wherein saidflexible circuit further comprises a controller connector, saidcontroller connector being configured to receive a battery controller,said connector being further configured to be in sensing relation toeach battery unit.